Extensible composite nonwoven fabrics

ABSTRACT

The present invention provides a composite nonwoven fabric with a superior combination of extensibility, tensile properties and abrasion resistance. The composite nonwoven fabric ( 10 ) comprises at least one layer containing multipolymer fibers, with a plurality of bonds bonding the fibers together to form a coherent extensible nonwoven web ( 11 ). This coherent extensible nonwoven web ( 11 ) has a Taber surface abrasion value (rubber wheel) of greater than 10 cycles and an elongation at peak load in at least one of the machine direction or the cross-machine direction of at least 70%. A second extensible layer ( 12 ) is laminated to this coherent extensible nonwoven web ( 11 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 08/997,082,filed Dec. 23, 1997, now abandoned , which in turn is a continuation ofapplication Ser. No. 08/676,360, filed Aug. 27, 1996, now U.S. Pat. No.5,804,286 issued on Sep. 8, 1998.

FIELD OF THE INVENTION

The invention relates to composite nonwoven fabrics, and moreparticularly to extensible nonwoven composite fabrics which are capableof elongating during mechanical stretching and which have excellentsurface abrasion resistance.

BACKGROUND OF THE INVENTION

Composite nonwoven fabrics are used in a variety of applications such asgarments, disposable medical products, diapers and personal hygieneproducts. New products being developed for these applications havedemanding performance requirements, including comfort, conformability tothe body, freedom of body movement, good softness and drape, adequatetensile strength and durability and resistance to surface abrasion,pilling or fuzzing. Accordingly, the composite nonwoven fabrics whichare used in these types of products must be engineered to meet theseperformance requirements.

In Sabee, U.S. Pat. Nos. 4,153,664 and 4,223,063, it is disclosed thatthe softness and drapeability of composite nonwoven fabrics, formed forexample from a meltblown or a spunbonded nonwoven fabric, can beimproved by drawing or stretching the fabric. More particularly,according to Sabee, the composite nonwoven fabrics are processed bydifferentially drawing or stretching the web to form a quilted patternof drawn and undrawn areas, providing a product with enhanced softness,texture and drapeability. However, while the stretching may improve somefabric physical properties, it can adversely affect other importantproperties, such as abrasion resistance, for example, leaving the fabricwith an unsightly fuzzed surface. In addition, Sabee teaches the use ofundrawn or underdrawn filaments in the use of this application. Undrawnor underdrawn filaments are typically higher in denier and therefore thefabrics tend to be stiff.

Often, the performance requirements of the product demand a compositenonwoven fabric having elasticity. In certain disposable diaper designs,for example, it is desired to impart elastic properties to the waistand/or to the leg cuff areas. One approach which has been taken toproviding such elastic properties in a composite nonwoven fabricinvolves forming and stretching an elastic web, then bonding agatherable web to the elastic web, and relaxing the composite. Anobvious limitation of this approach is having to form the composite inthe tensioned state. This requires additional equipment and controlsystems. Examples of this process are Mormon, U.S. Pat. No. 4,657,802,where it is disclosed that a composite nonwoven elastic is made by firststretching an elastic web, forming a fibrous nonwoven gatherable webonto the stretched elastic nonwoven, joining the two together to form acomposite structure, then allowing the composite to relax. In Collier,et al., U.S. Pat No. 5,169,706, it is disclosed that a composite elasticmaterial having a low stress relaxation is formed between an elasticsheet and a gatherable layer. In Daponte, U.S. Pat. No. 4,863,779, acomposite is disclosed which involves first tensioning the elasticelastic web to elongate it, bonding at least one gatherable web to theelastic web, and relaxing the composite immediately after bonding, sothat the gatherable web is gathered between the bond points.

Another approach to imparting elastic properties to a composite nonwovenfabric is with a so-called “zero-strain” stretchable laminate. A“zero-strain” stretchable laminate refers to a fabric in which at leasttwo layers of material, one elastic, the other substantially inelastic,are secured to one another along their coextensive surfaces while in asubstantially untensioned state. The fabric is subsequently subjected tomechanical stretching. The inelastic layer typically fractures orextends, thus permanently elongating the inelastic layer and producing acomposite fabric with elastic properties. This lamination and stretchingprocess is advantageous in that utilizing elastic in an unstretchedcondition is easier and less expensive than stretched elastic used intraditional processing operations. However, one problem which hasexisted with presently available “zero-strain” stretchable laminates Issurface abrasion. The mechanical stretching either fractures or disruptsthe fibers within the substantially inelastic component of the“zero-strain” laminate, and as a result, the fibers detach and aresusceptible to linting and pilling. In addition, such fracturing ordetachment causes a noticeable loss in fabric strength.

There have been attempts to address the aforementioned problems of fibertie down and fabric abrasion resistance. For example, attempts have beenmade to make the nonwoven fabric component of the composite with highelongation properties. Conventional polypropylene, which has been widelyused in producing nonwoven fabrics, provides adequate fuzz and abrasionresistance properties in the unstretched condition, but the elongationproperties are unacceptable and therefore the fibers and/or fabricsfracture. Nonwoven webs formed from linear low density polyethylene(LLDPE) have been shown to have high elongation properties and also topossess excellent hand, softness and drape properties, as recognized forexample in Fowells U.S. Pat. No. 4,644,045. However, such fabrics havenot found wide commercial acceptance, since they fail to provideacceptable abrasion resistance. The bonding of LLDPE filaments into aspunbonded web with acceptable abrasion resistance has proven to be verydifficult, since acceptable fiber tie down is observed at a temperaturejust below the point that the filaments begin to melt and stick to thecalender. Because of this very narrow bonding window and the resultingabrasion resistance and fuzz properties, spunbonded LLDPE nonwovens havenot found wide commercial acceptance for the aforementionedapplications.

SUMMARY OF THE INVENTION

The present invention overcomes these disadvantages and limitations andprovides a composite fine denier nonwoven fabric with a superiorcombination of extensibility, tensile properties and abrasionresistance. The composite nonwoven fabric of the present invention iscomprised of at least two layers, the first layer containingmultipolymer fibers with a plurality of bonds bonding the fiberstogether to form a coherent extensible nonwoven web. This coherentextensible nonwoven web has a Taber surface abrasion value (rubberwheel) of greater than 10 cycles and an elongation at peak load in atleast one of the machine direction or the cross-machine direction of atleast 70%. A second extensible layer is laminated to this coherentextensible nonwoven web.

The term “fibers” as used herein is intended to include both discretelength “staple” fibers and continuous filaments. According to oneembodiment of the present invention, the coherent extensible nonwovenweb is a thermally bonded spunbond nonwoven web of randomly arrangedsubstantially continuous filaments consisting of multiple polymers.According to another embodiment of the invention, the coherentextensible nonwoven web is a thermally bonded carded web of staplefibers. The coherent extensible nonwoven web may contain, in addition tothe multipolymer fibers, additional fibrous components, such asmeltblown microfibers. In accordance with the invention, the compositenonwoven fabric may include an optional third component laminated to theopposite side of the second extensible layer, which may, for example, bea film, another nonwoven web, or a composite fabric.

The second extensible layer to which the multipolymer fiber web islaminated can take various forms. For example, it may comprise acontinuous or perforated polymer film, a film or web of an elasticpolymer, another spunbonded nonwoven web, an extensible scrim or net, anarray of extensible or elastic strands, or a web of meltblownmicrofibers. Where an elastic web or film is used, the composite can bestretch activated by elongation, which causes permanent elongation andstretching of the coherent extensible web of multipolymer fibers, andthe resulting composite fabric exhibits elastic properties. Where anextensible nonelastic film layer is used, such as polyolefin film forexample, the composite can be stretch activated by elongation to atleast 20% of its original unstretched length, producing a compositehaving excellent softness and drape.

BRIEF DESCRIPTION OF THE DRAWINGS

Some of the features and advantages of the invention having been stated,others will become apparent from the detailed description which follows,and from the accompanying drawings, in which:

FIG. 1 is a schematic perspective view showing a nonwoven compositefabric in an unstretched state, with the layers and bonds beingexaggerated for clarity of illustration;

FIG. 2 is a perspective view showing a composite nonwoven fabric similarto FIG. 1 with an additional extensible layer being incorporated intothe composite fabric;

FIG. 3 is a perspective view showing the composite fabric of FIG. 1being elongated by mechanical stretching;

FIG. 4 is a side view of a diaper incorporating the composite fabric ofthis invention; and

FIGS. 5A and 5B are graphs showing the stress-strain relationships ofthe fabric sample described in Example 11 after a first and secondelongation, respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a composite nonwoven fabric in accordance with the presentinvention. As depicted, the composite 10 includes an extensible,nonelastic, nonwoven web 11 of multipolymer fibers laminated to a secondextensible layer 12 by an adhesive layer 13. By “extensible nonelastic”,it is meant that the web 11 can be relatively easily stretched beyondits elastic limit and permanently elongated by application of tensilestress. However, the web has little retractive force and is thereforenonelastic. The extensible nonelastic nonwoven web 11 comprises a layerof multipolymer fibers and a plurality of bonds B bonding the fiberstogether to form a nonwoven web which is coherent and extensible. Theweb 11 may be made by any of a number of manufacturing techniques wellknown in the nonwovens field.

For example, according to one embodiment of the invention, the coherentextensible nonwoven web 11 is a thermally bonded spunbond nonwoven webof randomly arranged substantially continuous filaments. The spunbondnonwoven web may be produced, for example, by the conventional spunbondprocess wherein molten polymer is extruded into continuous filamentswhich are subsequently quenched, attenuated by a high velocity fluid,and collected in random arrangement on a collecting surface. Afterfilament collection, any thermal, chemical or mechanical bondingtreatment may be used to form a bonded web such that a coherent webstructure results. In the embodiment shown in FIG. 1, the web 11 isbonded by plurality of intermittent bonds, indicated by the referencecharacter B. In this regard, thermal point bonding is most preferred.Various thermal point bonding techniques are known, with the mostpreferred utilizing calender rolls with a point bonding pattern. Anypattern known in the art may be used with typical embodiments employingcontinuous or discontinuous patterns. Preferably, the bonds B coverbetween 6 and 30 percent of the area of the web 11, more preferably 8 to20 percent, and most preferably, 12 to 18 percent of the layer iscovered. By bonding the web in accordance with these percentage ranges,the filaments are allowed to elongate throughout the full extent ofstretching while the strength and integrity of the fabric is maintained.

Alternatively, the extensible coherent nonwoven web 11 can be a cardednonwoven web of staple fibers. As known, carding is typically carriedout on a machine which utilizes opposed moving beds or surfaces of fine,angled, spaced apart teeth or wires to pull clumps of staple fibers intoa web. Fibers within the web are then subjected to bonding to form acoherent web structure by any suitable thermal, chemical or mechanicalbonding treatment. For example, thermal point bonds are formed in amanner previously described to impart strength and flexibility to thefabric.

In accordance with the invention, the staple fibers or continuousfilaments which form the extensible web 11 are multipolymer fibersformed of at least two polymer components For the purposes of theinvention, the term “polymer” is used in a general sense, and isintended to include homopolymers, copolymers, grafted copolymers, andterpolymers . The term blend is also used generally herein, and isintended to include immiscible and miscible polymer blends. The polymersare considered to be “immiscible” if they exist in separate, distinctphases in the molten state; all other blends are considered to be“miscible”. It is understood that varying levels of miscibility canexist, and are also intended to be within the scope of this invention.Blends with more than two polymers may also be utilized, including thosewith three or more polymer components. Both immiscible and misciblepolymers may be added to a two component blend to impart additionalproperties or benefits with respect to blend compatibility, viscosity,polymer crystallinity or phase domain size.

Since the blends employed in the invention will undergo extrusion,stabilizers and antioxidants are conventionally added to the polymerblend. Other additives may also be added in accordance with the presentinvention. For example inorganic additives such as titanium dioxide,talc, fumed silica or carbon black. The blend may also contain otheradditives, such as other polymers, diluents, compatibilizers,antiblocking agents, impact modifiers, plasticizers, UV stabilizers,pigments, delusterants, lubricants wetting agents, antistatic agents,nucleating agents, rheology modifiers, water and alcohol repellents, andthe like. It is also anticipated that additive materials which have anaffect on processing or product properties, such as extrusion,quenching, drawing, laydown, static and/or electrical properties,bonding, wetting properties or repellency properties may also be used incombination with the blend. In particular, polymeric additives may alsobe used in conjunction with the blends which impart specific benefits toeither processing and/or end use.

According to one broad aspect of the invention, the multipolymer fibersare formed of a polymer blend composed of two or more polymers. Thepolymers of the blend can be miscible, immiscible, or a combination ofmiscible and immiscible polymers. In one embodiment in accordance withthe invention, the polymers may exist as a dominant continuous phase andat least one substantially discontinuous dispersed phase. In the casewhere the blend exists as a dominant continuous phase and at least onediscontinuous phase, other polymers may also be present which are eithermiscible in one, or the other, or both polymer phases.

According to a further aspect of the invention, the multipolymer fibersare formed of a polymer blend including a relatively low modulus polymerand at least one higher modulus polymer. It is believed that thiscombination is particularly valuable when the low modulus polymer is thedominant phase and the higher modulus polymer is dispersed therein. Itis theorized that the higher modulus polymer acts to ‘reinforce’ the lowmodulus dominant phase, lending stability to spinning, and stiffeningthe web just enough to allow for higher bond temperatures while reducingthe risk of the web sticking to and wrapping the calender. In the caseof multipolymer fibers formed of an immiscible polymer blend it isbelieved that the small amount of the dispersed polymer may have theeffect of wind up speed suppression (WUSS) on the dominant polymer phaseas described by Brody in U.S. Pat. No. 4,518,744. Wind up speedsuppression occurs when a small amount of an immiscible additiveeffectively reduces the degree of molecular orientation within the fiberat a given filament spinning velocity. The result is a filament withgenerally higher elongation and lower tenacity.

In yet another aspect of the invention, the multipolymer fibers areformed of a polymer blend composed of a dominant continuous phase, andat least one polymer, having low mutual affinity with the dominantphase, dispersed therein, and at least one additional polymer which isat least partially miscible in one or the other or both continuous anddispersed polymer phases. If the one additional polymer is miscible inthe dominant phase, and effectively reduces its crystallinity, it isbelieved that the improved extensibility observed in the resultingcomposites may be due to an ‘impact-modifying’ effect. If the oneadditional polymer has an affinity for both polymers, or serves to lowerthe surface energies between the two phases, it is believed that theimprovement observed in the composite extensibility is due to acompatibilization effect. Independent of theory, the blend mustultimately form filaments or fibers, which when formed into webs andcomposite structures exhibit the properties described by the invention,meaning low fuzz and good elongation.

In one embodiment, the multipolymer fibers may comprise from 1 to 50percent by weight polyethylene and from 99 to 50 percent by weightpropylene polymer. Fabrics formed from such blends exhibit low fuzz andgood elongation.

In applications where tensile strength is particularly important andhigh elasticity is of lesser concern, the composite fabric may include acoherent, extensible nonwoven web 11 formed of fibers of apolyethylene-propylene polymer blend where the polyethylene is presentin the range of 1% to 10% and the propylene polymer is present in therange of 90% to 99% by weight. In still another embodiment, verysubstantial and surprising increases in elongation can be achieved byblending a third polymer component into the blend. For example, themultipolymer fibers may include a dominant amount of a propylenepolymer, such as isotactic polypropylene, a small amount of a polymerhaving low mutual affinity with the dominant polymer, such aspolyethylene, and an additional third polymer which either reducescrystallinity and/or compatibilizes the blend. What results is a softerweb, with extremely high extensibility. Preferred multipolymer fibersaccording to this embodiment may comprise greater than 50 percent byweight propylene polymer, 1 to 10 percent polyethylene, and 10 to 40percent of the third polymer. Suitable additional third polymers includepropylene copolymers and terpolymers such as the commercially availableCatalloy™ copolymers available from Montell. These resins arecharacterized by having the comonomer(s) exist to some degree in blocks,and wherein at least some portion of the polymer chain is miscible withone or the other, or both, dominant and dispersed polymer phases. Othersuitable polymers are the Reflex™ flexible polyolefins from Rexene.These crystallinity reducing resins are characterized as having atacticsegments present in the polymer chain, such that the “tacticity” of thepolymer is affected. Especially preferred multipolymer fibers accordingto this embodiment comprise 65 to 80 percent isotactic polypropylene, 1to 5 percent polyethylene, and 15 to 30 percent of a polyolefincopolymer wherein at least a portion of the chain is miscible withisotactic polypropylene.

Another class of useful and advantageous products according to thisaspect of the invention employ multipolymer fibers formed of a polymerblend comprised of a soft, extensible polymer phase, and at least oneadditional polymer having low mutual affinity with the soft, extensiblephase, such that it modifies either the rheological, mechanical, and/orthermal properties of the fibers in a way that improves processability(e.g. melt spinning), bonding and/or abrasion resistance whilemaintaining high extensibility. In a preferred embodiment the soft,extensible phase is present as a dominant, continuous phase. Forexample, polyethylene can be used as the soft, extensible dominant phaseand a propylene polymer as the additional modifying polymer. In apreferred embodiment the additional polymer is added in a smallproportion relative to the dominant phase. In another preferredembodiment, the additional polymer exhibits higher viscosity relative tothe dominant phase. Blending a relatively small proportion of the higherof viscosity propylene polymer, with the soft, extensible polyethylenepolymer, imparts greatly increased abrasion resistance to a nonwovenfabric formed from the polymer blend, without significant adverse effectupon other important fabric properties, such as extensibility, softness,tensile strength, etc. The spinnability of the polyethylene is alsoimproved by the presence of the additional propylene polymer. Accordingto this embodiment, the fibers preferably comprise between 2 to 50percent by weight of the propylene polymer, e.g. 3% ethylene-propylenecopolymer, and 98 to 50 percent by weight of the soft, extensiblepolymer, e.g. polyethylene. In one particularly preferred embodiment,the fiber composition may range from 5 to 40 percent by weight propylenepolymer, and most desirably between 5 to 25 percent by weight propylenepolymer and 75 to 95 percent by weight polyethylene. Especially suitedfor applications requiring good extensibility, tensile strength andabrasion resistance are fiber compositions of from 5 to 25 percent byweight propylene polymer. A most preferred embodiment contains 5 to 25percent by weight of ethylene-propylene copolymer or terpolymer and 75to 95 percent by weight linear low density polyethylene. In theseembodiments, the lower melting polyethylene is present as asubstantially continuous phase in the blend and the higher meltingpropylene polymer is present as a discontinuous phase dispersed in thepolyethylene phase.

In producing the fibers, the polyethylene and propylene polymercomponents are combined in appropriate proportion al amounts andintimately blended before being melt-spun. In some cases sufficientmixing of the polymer components may be achieved in the extruder as thepolymers are converted to the molten state.

Various types of polyethylene may be employed. As an example, a branched(i.e., non-linear) low density polyethylene or a linear low densitypolyethylene (LLDPE) can be utilized and produced from any of the wellknown processes, including metallocene and Ziegler-Natta catalystsystems. LLDPE is typically produced by a catalytic solution or fluidbed process under conditions established in the art. The resultingpolymers are characterized by an essentially linear backbone. Density iscontrolled by the level of comonomer incorporated into the otherwiselinear polymer backbone. Various alpha-olefins are typicallycopolymerized with ethylene in producing LLDPE. The alpha-olefins whichpreferably have four to eight carbon atoms, are present in the polymerin an amount up to about 10 percent by weight. The most typicalcomonomers are butene, hexene, 4-methyl-1-pentene, and octene. Ingeneral, LLDPE can be produced such that various density and melt indexproperties are obtained which make the polymer well suited formelt-spinning with polypropylene. In particular, preferred densityvalues range from 0.87 to 0.95 g/cc (ASTM D-792) and melt index valuesusually range from 0.1 to about 150 g/10 min. (ASTM D1238-89, 190° C.).Preferably, the LLDPE should have a melt index of greater than 10, andmore preferably 15 or greater for spunbonded filaments. Particularlypreferred are LLDPE polymers having a density of 0.90 to 0.945 g/cc anda melt index of greater than 25. Examples of suitable commerciallyavailable linear low density polyethylene polymers include thoseavailable from Dow Chemical Company, such as ASPUN Type 6811 (27 MI,density 0.923), Dow LLDPE 2500 (55 MI, 0.923 density), Dow LLDPE Type6808A (36 MI, 0.940 density), and the Exact series of linear low densitypolyethylene polymers from Exxon Chemical Company, such as Exact 2003(31 MI, density 0.921).

Various propylene polymers made by processes known to the skilledartisan may also be employed. In general, the propylene polymercomponent can be an isotactic or syndiotactic propylene homopolymer,copolymer, or terpolymer. Examples of commercially available propylenehomopolymers which can be used in the present invention include SOLTEXType 3907 (35 MFR, CR grade), HIMONT Grade X10054-12-1 (65 MFR), ExxonType 3445 (35 MFR), Exxon Type 3635 (35 MFR) AMOCO Type 10-7956F (35MFR), and Aristech CP 350 J (melt flow rate approximately 35). Examplesof commercially available copolymers of propylene include Exxon 9355which is a random propylene copolymer with 3% ethylene, 35 melt flowrate; Rexene 13S10A, a 10 melt flow rate random propylene copolymer with3% ethylene; Fina 7525MZ, an 11 melt flow rate 3% ethylene randompropylene copolymer, Montel EPIX 30F, a 1.7% ethylene, 8 melt flow raterandom copolymer of propylene. When the propylene polymer is thedominant continuous phase of the blend, the preferred melt flow rate isgreater than 20. When the propylene polymer exists as the dispersedphase of the blend, the preferred melt flow rate is less than 15 andmost preferably less than 10. In still another embodiment, themultipolymer fibers of the web 11 may be bicomponent or multicomponentfibers or filaments. The term bicomponent or multicomponent refers tothe existence of the polymer phases in discrete structured domains, asopposed to blends where the domains tend to be dispersed, random orunstructured. The polymer components can be configured into any numberof configurations including sheath-core, side-by-side, segmented pie,islands-in-the-sea, or tipped multilobal. A coherent extensible nonwovenweb can be made, for example, from a sheath-core bicomponent fiberhaving a polyester core and a polyethylene sheath. Alternatively, theextensible web 11 can comprise a single web containing a combination ofspunbonded filament and meltblown fibers or a combination of cardedstaple fibers and meltblown fibers.

The extensible nonwoven web 11, in all embodiments in accordance withthe present invention, is characterized by having high surface abrasionresistance and high elongation. The surface abrasion resistance of theweb may be conveniently measured objectively by physical tests which arestandard in the industry, such as the Taber abrasion test as defined byASTM Test Method D-3884-80. Extensible webs useful in the compositefabrics of the present invention are characterized by having a Taberabrasion value (rubber wheel) of greater than 10 cycles. Webs useful inthe composite fabrics of the present invention are further characterizedby having an elongation at peak load (ASTM D-5 1682) in either themachine direction (MD) or in the cross-machine direction (CD) or both ofat least 70 percent, more preferably at least 100 percent, and mostdesirably at least 150 percent. The multipolymer fibers of the web 11are of relatively fine diameter, typically 10 denier or less.

The second extensible layer 12 of the composite fabric 10 can exist invarious forms. According to one embodiment, it is a polyolefin film,most preferably a nonelastic polyolefin film that is extensible at least100 percent of its original length. The film preferably has a basisweigh t within the range of 10 to 40 grams per square meter. The presentinvention is particularly applicable to extensible film/fabriccomposites where the film of the type conventionally used as theimpermeable outer component of a disposable diaper.

The extensible layer 12 can also be an elastic layer of various formsincluding webs of bonded filaments, nets, films, foams, parallel arraysof filaments, and the like. Preferably, a film is employed. Suchstructures are produced by conventional methods known to the skilledartisan. For purposes of the present invention, an “elastic” layer isdefined as having a 75% recovery after a single extension of 10% of theoriginal dimension. As also known, any suitable elastomeric formingresins or blends thereof may be utilized in producing the abovestructures. Such suitable materials include the diblock and triblockcopolymers based on polystyrene (S) and unsaturated or fullyhydrogenated rubber blocks. The rubber blocks can consist of butadiene(B), isoprene (I), or the hydrogenated version, ethylene-butylene (EB).Thus, S-B, S-I, S-EB, as well as S-B-S, S-I-S, and S-EB-S blockcopolymers can be used. Preferred elastomers of this type include theKRATON polymers sold by Shell Chemical Company or the VECTOR polymerssold by DEXCO. Other elastomeric thermoplastic polymers includepolyurethane elastomeric materials such as ESTANE sold by B.F. GoodrichCompany; polyester elastomers such as HYTREL sold by E.I. Du Pont DeNemours Company; polyetherester elastomeric materials such as ARNITELsold by Akzo Plastics; and polyetheramide materials such as PEBAX soldby Elf Atochem Company; polyolefin elastomers such as Insite™, Affinity™or Engage™ polyethylene plastomers from Dow Chemical or the Exact™polyethylene plastomers available from Exxon Chemical. Crosslinkedelastomers such as crosslinked urethanes and rubbers may also beemployed. Blends of these polymers with other polymers, such as, forexample, polyolefins may be employed to enhance processing such asdecreasing melt viscosity, allowing for lower melt pressures andtemperatures and/or increase throughput.

In accordance with the invention, the composite fabric 10 is formed bylaminating nonelastic extensible web 11 and extensible web 12, with orwithout an adhesive, utilizing any of the well established thermal orchemical techniques Including thermal point bonding, open-nip thermallamination, through air bonding, needlepunching, and adhesive bonding,with adhesive bonding being preferred. A suitable adhesive, if desired,is applied either to web 11, to extensible web 12, or to both, as eithera continuous or discontinuous coating, to form an adhesive layer 13.Where a continuous adhesive coating is employed, the adhesive layer 13should be relatively thin and the adhesive should be sufficientlyflexible or extensible to allow the filaments to elongate uponstretching. Where a discontinuous adhesive is employed, any intermittentpattern can be used such as, for example, lines, spirals, or spots, andthe adhesive can be less extensible. The adhesive can be appliedcontinuously or intermittently by any accepted method includingspraying, slot coating, meltblowing and the like.

Suitable adhesives can be made from a variety of materials includingpolyolefins, polyvinyl acetate polyamides, hydrocarbon resins, waxes,natural asphalts, styrenic rubbers, and blends thereof. Preferredadhesives include those manufactured by Century Adhesives, Inc. ofColumbus, Ohio and marketed as Century 5227 and by H.B. Fuller Companyof St. Paul, Minn. and marketed as HL-1258.

In assembling the composite fabric 10, layers 11 and 12 are provided inan unstretched state from individual supply rolls. If desired, adhesiveis then applied over the surface of extensible web 11 or layer 12. Soonafter the adhesive is applied, the layers are subjected to pressure thusforming fabric 10. For example, the layers can be fed through calendernip rolls. Alternatively, the fabric can be bonded by thermal means withor without an adhesive.

In a further embodiment depicted in FIG. 2, the composite fabric 10′includes an additional component 14 on the side of extensible web 12opposite layer 11 to form a trilaminate. This third component may or maynot be extensible. Any suitable material may be employed in variousforms such as, for example, woven or nonwoven material, films orcomposites, such as a film-coated nonwoven. In the particular embodimentshown in FIG. 2, the component 14 is a nonelastic extensible polymericfilm. Typically, a thermoplastic polymer film is used with preferredpolymers being polypropylene or polyethylene. Commercially desirablefilms includes those manufactured by Tredegar Industries, Inc. of TerreHaute, Ind. If the component 14 is substantially impervious to liquids,it can be suitably employed as a back sheet in personal garmentapplications such as diapers, training pants, incontinence briefs andfeminine hygiene products. Any well known techniques for laminatingcomponent 14 to the composite structure may be utilized; preferably,component 14 is laminated by a thin layer 15 of adhesive in a mannerpreviously described.

Alternatively, component 14 can be a nonwoven web, which can beconstructed to be extensible or essentially nonextensible. For example,the nonwoven web may be another web of multipolymer fibers similar toweb 11 so that a fibrous web is used on both faces of the compositefabric 10′. An essentially nonextensible nonwoven web can also beemployed, such as a carded thermally point bonded web of low elongationfibers such as Hercules Type 196 polypropylene staple fibers.

Referring to FIG. 3, stretching forces are applied to composite fabric10 to extend and elongate the fabric in the machine direction (MD)and/or cross-machine direction (CD). Numerous established techniques canbe employed in carrying out this operation. For example, a common wayfor obtaining MD elongation is to pass the fabric through two or moresets of nip rolls, each set moving faster than the previous set. CDelongation may be achieved through tentering. Other means may beemployed; for example, “ring rolling” as disclosed in U.S. Pat. No.5,242,436 to Weil et al., incorporated herein by reference, is oftenused in obtaining CD and/or MD elongation.

Upon application of elongation forces (denoted by F) on fabric 10,fibers within extensible layer 11 oriented in the direction of theelongation experience tension and the fabric and fibers undergodeformation. During this process, the fibers are capable of elongatingwell beyond their unstretched length. As an example, fabric elongationbetween 70 and 300 percent is often realized. In most instances, thefibers are elongated past their elastic limit, undergo plasticdeformation, and become permanently extended. In accordance with theinvention, intermittent bonds B distributed throughout nonelastic layer11 are of high strength such that fibers are sufficiently tied downwithin the nonelastic layer 11 and fiber detachment is minimized duringthe elongation process. Accordingly, fiber detachment is reduced withthe desirable result that abrasion resistance is maintained and fuzzingis minimized. Moreover, fabric strength is maintained as the coherentweb structure is kept intact during the elongation operation.

The fabric 10 is particularly well suited for use in various disposablegarments such as diapers, training pants, incontinence briefs andfeminine hygiene products. The fabric may be utilized in a diaper, suchas the one illustrated in FIG. 4 (denoted as 20) having a waist region21 and leg cuff components 22. Since the composite fabric 10 is bothsoft and strong, the diaper can withstand rigorous movement of thewearer without rubbing or chafing the wearer's skin during use.

The following examples serve to illustrate the invention but are notintended to be limitations thereon.

EXAMPLE 1

This example illustrates the benefits of various multipolymer systems inproducing low fuzz, highly extensible spunbond nonwoven fabrics, andcompares the fabric properties to a conventional spunbond fabric made of100 percent isotactic polypropylene. Continuous filament spunbondnonwoven fabrics were produced under generally similar conditions fromdifferent multipolymer blend combinations, as follows: Sample A: a 26g/m² spunbond fabric consisting of 96% isotactic polypropylene and 4%polyethylene (Dow 05862N); Sample B: a 33 g/m² spunbond fabricconsisting of 76% isotactic polypropylene, 20% propylene copolymer(Montell KS057P), and 4% polyethylene (Dow 05862N); Sample C: a 33 g/m²spunbond fabric consisting of 85% polyethylene (Dowlex 2553) and 15%ethylene-propylene copolymer (Amoco 8352); and Sample D: a 60 g/m²spunbond-meltblown-spunbond composite fabric consisting of bicomponentspunbond filaments (polyester core, polyethylene sheath) and meltblownpolyethylene. The fabric tensile strength and peak elongation propertieswere measured in the machine direction (MD) and in the cross-machinedirection (CD) according to ASTM D-1682. The Taber abrasion resistanceof the fabrics were measured according to ASTM D-3884, using both therubber wheel test and the felt wheel test. The results are shown inTable 1, below. For comparison, a commercially available 100% isotacticpolypropylene spunbond fabric produced by Fiberweb North America underthe trademark Celestra®, was also tested, and reported i n Table 1 asSample E. It was not tested for fuzz, since it failed the elongationcriteria.

TABLE 1 Physical Properties of High Elongation Multi-Polymer NonwovenFabrics MD CD MD CD Taber Abrasion (cycles) Tensile Tensile Elong.Elong. Rubber Felt Sample (g/cm) (g/cm) (%) (%) Wheel Wheel A 1144  307132 121 79  800 B 1325 578 215 191 71 1050 C 610 263 141 188 124  1300 D1764  507 154 133 127  2650 E 768 553  38  44 nt* nt* *nt = not tested.This material fails the elongation criteria and therefore was not testedfor fuzz.

EXAMPLE 2

Ninety percent by weight of a linear low density polyethylene (LLDPE)with a melt flow of 27 (Dow 6811 LLDPE) and ten percent by weight of apolypropylene (PP) polymer 20 with a melt flow approximately 35(Aristech CP 350 J) were dry blended in a rotary mixer. The dry-blendedmixture was then introduced to the feed hopper of an extruder of aspunbond nonwoven spinning system. Continuous filaments were meltspun bya slot draw process at a filament speed of approximately 600 m/min anddeposited upon a collection surface to form a spunbond nonwoven web, andthe web was thermally bonded using a patterned roll with 12% bond area.For comparison purposes, nonwoven spunbond fabrics were produced undersimilar conditions with the same polymers, using 100% PP and 100% LLDPE.

As shown in Table 2, the 100% LLDPE spunbond samples exhibited superiorsoftness (75 and 77.5) compared to the 100% polypropylene spunbondsample (30). However, the abrasion resistance of the 100% LLDPE sample,as seen from the fuzz measurement, was relatively high (12.5 and 2.4)compared to the 100% PP sample (0.3). The nonwoven fabric formed fromthe 90% LLDPE/10% PP blend had a high softness (67.5) only slightly lessthan the 100% LLDPE fabric, and had abrasion resistance (fuzz value) of1.0 mg., which is significantly better than the values seen for 100%LLDPE. The blend sample also showed improved CD tensile compared toproducts made with 100% LLDPE.

TABLE 2 Sample A B C D C = comparison I = invention C C C I Composition:% polypropylene 100 0 0 10 % polyethylene 0 100 100 90 filament dia.(microns) 17.5 20.9 20.9 22.5 Basis weight (gsm)¹ 23.1 25.2 24.6 24.8Loft @ 95 g/in² (mils)² 9.8 9.0 7.8 9.3 Fuzz (mg)³ 0.3 12.5 2.4 1.0Softness⁴ 30 75 77.5 67.5 Strip Tensile (g/cm)⁵ CD 557 139 157 164 MD1626 757 639 467 Peak Elongation (%) CD 90 116 129 108 MD 93 142 106 119TEA (in. g./in CD 852 297 346 354 MD 2772 2222 1555 1389 ¹gsm = gramsper square meter ²Loft was determined by measuring the distance betweenthe top and the bottom surface of the fabric sheet while the sheet wasunder compression loading of 95 grams per square inch. The measurementis generally the average of 10 measurements. ³Fuzz is determined byrepeatedly rubbing a soft elastomeric surface across the face of thefabric a constant number of times. The fiber abraded from the fabricsurface is then weighed. Fuzz is reported as mg weight observed.⁴Softness was evaluated by an organoleptic method wherein an expertpanel compared the surface feel of Example Fabrics with that ofcontrols. Results are reported as a softness score with higher valuesdenoting a more pleasing hand. Each reported value is for a singlefabric test sample, but reflects the input of several panel members.⁵Tensile, Peak Elongation and TEA were evaluated by breaking a one inchby seven inch long sample generally following ASTM D1682-64, theone-inch cut strip test. The instrument cross-head speed was set at 5inches per minute and the gauge length was set at 5 inches per minute.The Strip Tensile Strength, reported as grams per centimeter, isgenerally the average of at least 8 measurements. Peak Elongation is thepercent increase in length noted at maximum tensile strength. # TEA,Total Tensile Energy Absorption, is calculated from the area under thestress-strain curve generated during the Strip Tensile test.

EXAMPLE 3 (Control)

A control fiber was made by introducing 100% Dow LLDPE 2500 (55 MI,0.923 density) to a feed hopper of a spinning system equipped with anextruder, a gear pump to control polymer flow at 0.75 gram per minuteper hole, and a spinneret with 34 holes of L/D=4:1 and a diameter of 0.2mm. Spinning was carried out using a melt temperature in the extruder of215° C. and a pack melt temperature of 232° C. After air quench, theresulting filaments were drawn down at a filament speed of approximately1985 m/min using an air aspiration gun operating at 100 psig to yield adenier of 3.01 and denier standard deviation of 0.41.

EXAMPLE 4

Ninety parts by weight of Dow LLDPE Type 2500 (55 MI, 0.923 density) andten parts of Himont X10054-12-1 polypropylene (65 MFR) were dry blendedin a rotary mixer and then introduced to the feed hopper of the spinningsystem described in Example 2. Spinning was carried out using a packmelt temperature of 211° C. After air quench, the resulting filamentswere drawn down at a filament speed of approximately 2280 M/Min using anair aspiration gun operating at 100 psig to yield a denier of 2.96 and adenier standard deviation of 1.37.

EXAMPLE 5

Ninety parts by weight of Dow LLDPE Type 2500 (55 MI, 0.923 density) andten parts of Soltex 3907 polypropylene (35 MFR, 1.74 die swell, CRgrade) were dry blended in a rotary mixer and then introduced to thefeed hopper of the spinning system described in Example 2. Spinning wascarried out using a pack melt temperature of 231° C. and an extrudermelt temperature of 216° C. After air quench, the resulting filamentswere drawn down at a filament speed of approximately 2557 M/Min using anair aspiration gun operating at 100 psig to yield a denier of 2.64 and adenier standard deviation of 0.38.

EXAMPLE 6

Ninety parts by weight of Dow LLDPE Type 6808A (36 MI, 0.940 density)and ten parts of Soltex 3907 polypropylene (35 MFR, 1.74 die swell, CRgrade) were dry blended in a rotary mixer and then introduced to thefeed hopper of the spinning system described in Example 3. Spinning wascarried out using a pack melt temperature of 231° C. and an extrudermelt temperature of 216° C. After air quench, the resulting filamentswere drawn down at a filament speed of approximately 2129 M/Min using anair aspiration gun operating at 100 psig to yield a denier of 3.17 and adenier standard deviation of 2.22.

The quality of spinning for a given formulation has been found toroughly correlate with the denier standard deviation. A reduced standarddeviation suggests more stable or higher quality spinning. Thus it isunexpected and contrary to the teaching of the prior art that the blendusing a 35 MFR polypropylene in Example 5 yielded a more stable spinningthan seen with the corresponding LLDPE control in Example 3.

EXAMPLE 7

Eighty parts by weight of a linear low density polyethylene pellets of55 melt index and 0.925 g/cc density and twenty parts by weightpolypropylene pellets of 35 melt flow rate were dry blended in a rotarymixer. The dry-blended mixture was then introduced to the feed hopper ofa spinning system equipped with an extruder with a 30:1 l/d ratio, astatic mixer, and a gear pump for feeding the molten polymer to a heatedmelt block fitted with a spinneret. Filaments were extruded from thespinneret and drawn using air aspiration.

EXAMPLE 8

Samples of continuous filament spunbonded nonwoven webs were producedfrom blends of a linear low density polyethylene with a melt flow rateof 27 (Dow 6811A LLDPE) and a polypropylene homopolymer (Appryl 3250YR1,27 MFR) in various blend proportions. Control fabrics of 100 percentpolypropylene and 100 percent polyethylene were also produced undersimilar conditions. The fabrics were produced by melt spinningcontinuous filaments of the various polymers or polymer blends,attenuating the filaments pneumatically by a slot draw process,depositing the filaments on a collection surface to form webs, andthermally bonding the webs using a patterned calender roll with a 12percent bond area. The fabrics had a basis weight of approximately 25gsm and the filaments had an average mass/length of 3 dtex. The tensilestrength and elongation properties of these fabrics and their abrasionresistance were measured, and these properties are listed in Table 3. Asshown, the 100 percent polypropylene control fabric had excellentabrasion resistance, as indicated by no measurable fuzz generation;however the fabrics had relatively low elongation. The 100 percentpolyethylene control fabric exhibited go d elongation properties, butvery poor abrasion resistance (high fuzz values and low Taber abrasionresistance) and relatively low tensile strength. Surprisingly, thefabrics of the invention made of blends of polypropylene andpolyethylene exhibited an excellent combination of abrasion resistance,high elongation, and good tensile strength. It is noted that the CDelongation values of the blends actually exceeded that of the 100%polyethylene control. This surprising increase in elongation is believedto be attributable to the better bonding of the filaments of the blendas compared to the bonding achieved in the 100% polyethylene control,which resulted in the fabrics of the invention making good use of thehighly elongatable filaments without bond failure.

EXAMPLE 9

Samples of continuous filament spunbonded nonwoven webs of basis weightapproximately 25 grams/square meter were produced from blends of alinear low density polyethylene with a melt flow rate of 27 (Dow 6811ALLDPE) and a polypropylene homopolymer (either Appryl 3250 YR1 orAristech CP350J) in various blend proportions. Control fabrics of 110percent polypropylene and 100 percent polyethylene were also producedunder similar conditions. The fabrics were produced by melt spinningcontinuous filaments of the various polymers or polymer blends,attenuating the filaments pneumatically by a slot draw process,depositing the filaments on a collection surface to form webs, andthermally bonding the webs using a patterned calender roll with a 12percent bond area. The tensile strength and elongation properties ofthese fabrics and their abrasion resistance were measured, and theseproperties are listed in Table 3. As shown, the 100 percentpolypropylene control fabric had excellent abrasion resistance, asindicated by no measurable fuzz generation; however the fabrics had verylow elongation, thus limiting the utility of such fabrics in extensiblefilm/fabric laminates. The 100 percent polyethylene control fabricexhibited excellent elongation properties, but very poor abrasionresistance (high fuzz values) and relatively low tensile strength.Surprisingly, the fabrics made of polypropylene/polyethylene blendsexhibited an excellent combination of abrasion resistance, highelongation, and good tensile strength. The high filament elongationmakes the fabrics well suited for use in an extensible film/fabriccomposite structure.

EXAMPLE 10

A polyethylene film of approximately 1.5 mil thickness, such as is usedin a disposable diaper backsheet, was sprayed with an all purposeadhesive (Locktite Corporation) and was bonded by application ofpressure to a 25 gsm spunbond fabric containing 15% polypropylene and85% polyethylene, one of the nonwoven fabrics described in Example 9.The cross machine direction of the fabric coincided with the crossmachine direction of the film. The composite fabric of film andpolypropylene/polyethylene spunbond nonwoven was then extended to 200%extension in the CD direction, beyond the elastic limit of the spunbondfabric, by an Instron tensile tester. The resulting elongated compositefabric was found to exhibit reduced basis weight, desirable softness anddrape properties, and was surprisingly free of detached fibers and lint,thus showing no unsightly fuzzed appearance. The extended compositefabric was thicker in appearance than its unextended precursor. Theelongated fabric can be used as a diaper backside or diaper leg cuffs.

TABLE 3 MECHANICAL PROPERTIES OF POLYPROPYLENE (PP)/POLYETHYLENE (PE)BLEND FABRICS Taber Taber Abrasion Abrasion MD CD MD CD (cycles-(cycles- Tensile Tensile Elong Elong Fuzz rubber felt Fabric (g/cm)⁶(g/cm)¹ (%)¹ (%)¹ (mg)⁷ wheel)⁸ wheel)³ 100% 925 405 62 70 0.0 40 733 PP50/50 1110 415 147 145 0.3 — — PP/PE 25/75 764 273 170 190 0.3 32 200PP/PE 15/85 676 277 199 224 0.5 22 500 PP/PE 10/90 426 170 109 141 0.3 —— PP/PE 100% 296 63 168 131 19.0 10  15 PE ⁶Tensile and Peak Elongationwere evaluated by breaking a one inch by seven inch long samplegenerally following ASTM D1682-64, the one-inch cut strip test. Theinstrument cross-head speed was set at 5 inches per minute and the gaugelength was set at 5 inches per minute. The Strip Tensile Strength,reported as grams per inch, is generally the average of at least 8measurements. Peak Elongation is the percent increase in length noted atmaximum tensile strength. ⁷Fuzz is determined by repeatedly rubbing asoft elastomeric surface across the face of the fabric a constant numberof times. The fiber abraded from the surface is then weighed. Fuzz isreported as mg weight observed. ⁸Conducted according to ASTM D3884-80where the number of cycles was counted until failure. Failure wasdefined as the appearance of a hole of one square millimeter or greaterin the surface of the fabric.

EXAMPLE 11

An elastic film of 1.5 mil thickness was cast from Hytrel 8122 polyesterelastomer sold by E.I. Du Pont DeNemours Company. A sample of theelastic film was sprayed with an all purpose adhesive (LocktiteCorporation) and was bonded by application of pressure to a 25 grams persquare meter spunbonded fabric containing 15% polypropylene and 85%polyethylene (one of the nonwoven fabric samples described in Example9). The cross machine direction of the fabric coincided with the machinedirection of the film. A 1.5 inch wide sample of the resulting compositewas placed in the jaws of an Instron tensile tester and elongated to200% extension.

The composite was returned to 0% extension. The resulting stress-straincurve is given in FIG. 5A. The spunbonded component remained attached tothe elastic film but the filaments were elongated, so that theunextended composite had a bulky appearance. The composite was elongateda second time to 200% extension and then returned to 0% extension. Theresulting stress-strain curve is given in FIG. 5B. The modulus ofelasticity was much lower for the second extension, because thefilaments of the spunbonded component were no longer resisting theextension. The composite had stretch behavior characteristic of anelastic material.

EXAMPLE 12

A fabric of the invention (Fabric A) was prepared by thermal pointbonding three polyolefin webs placed in juxtaposition. These webs weremelt spun from the following polymers:

Outer layer #1−8.5 grams per square meter 96% polypropylene (Exxon3445)/4% polyethylene (Dow 05862N) Middle Layer—2 grams per square meter100% polypropylene (Exxon 3546G) meltblown fibers

Outer layer #2—8.5 grams per square meter 96% polypropylene (Exxon3445)/4% polyethylene (Dow 05862N)

The average fiber size in the outer layers was 3.3 dtex. The averagefiber diameter in the middle layer was 1.9 microns. The webs were bondedusing a set of calender rolls with 17% bond area. The mechanicalproperties of this fabric, as well as those of a control fabric made of100% polypropylene (Fabric B) are given in Table 3. The higherelongation of the fabric containing polyethylene in the filaments of theouter layers is clearly evident.

A sample of this trilaminate fabric (Fabric A) is inserted as a barriercuff component into a diaper of the design described in U.S. Pat. No.4,738,677. This diaper also incorporates a fastening system as describedin U.S. Pat. No. 5,242,436. In this diaper, the above polyolefintrilaminate (Fabric A) is adhesively attached to a section of elasticfoam in the side panel region of the diaper. The resulting elasticlaminate is subjected to 33% extension. The thermal point thermal bondsof the inelastic trilaminate component remain intact while the filamentsconnecting the bonds are elongated. The result is that the side panelsection of the diaper becomes stretchable, the elastic.foam dominatingits stress-strain characteristics.

EXAMPLE 13

Spunbond-meltblown-spunbond trilaminate fabrics were produced usingspunbond outer webs of continuous filament multipolymer fibers of 4%polyethylene and 96% polypropylene and an inner extensible web ofpolypropylene meltblown microfibers having a maximum fiber diameter of 5microns. The composite fabric was bonded by passing it through a heatedcalender at a temperature of 145° C. with the patterned roll of thecalender producing a bond area of about 17 percent. The trilaminatefabrics were tested for 5 tensile properties and the barrier propertiesof the composites were measured by a rising water column strikethroughtest. The results are shown in Table 4.

TABLE 4 Sample F G H I Total basis weight (g/m²) 19.21 20.2 23.45 22.1Thickness (mm) 0.181 0.22 Spunbond denier (dpf) top 3.5 3.0 3.0 3.3bottom 3.0 3.5 Meltblown fiber dia. top 1.95 1.69 (microns) bottom 1.741.75 Tensile strength (g/in) MD 1828 1439.0 1836.0 1504.0 CD 424.4 512.4530.7 588.8 Max. elongation (%) MD 97.9 113.6 100.5 97.8 CD 82.0 95.981.1 82.2 Break elongation (%) MD 113.5 127.9 116.3 108.3 CD 116.5 135.8105.5 114.2 TEA (cm-g/cm²) MD 627.6 526.0 648.4 485.4 CD 123.2 201.2151.1 203.2 Rising water column 111.9 11.6 209.9 246 (MM)

The invention has been described in considerable detail with referenceto its preferred embodiments. However, it will be apparent that numerousvariations and modifications can be made without departure from thespirit and scope of the invention as described in the foregoingspecification and defined in the appended claims.

That which we claim:
 1. A nonwoven fabric comprising multipolymer fibersbonded by a plurality of bonds to form a coherent extensible nonwovenweb, said coherent extensible nonwoven web having a Taber surfaceabrasion value (rubber wheel) of greater than 10 cycles and anelongation at peak load in at least one of the machine direction or thecross-machine direction of at least 70 percent, and said multipolymerfibers comprising a blend of at least two polymers which are immisciblewith one another and at least one additional polymer which is miscibleor partially miscible with said immiscible polymers.
 2. A nonwovenfabric according to claim 1, wherein said blend of immiscible polymersis comprised of a dominant, continuous phase and at least one dispersedphase.
 3. A nonwoven fabric according to claim 2, wherein said blend ofimmiscible polymers comprises a propylene polymer and polyethylene.
 4. Anonwoven fabric according to claim 3, wherein said polyethylene islinear low density polyethylene and said propylene polymer is apropylene copolymer or terpolymer.
 5. A nonwoven fabric according toclaim 4, wherein said polyethylene is a linear low density polyethylenepolymer of a melt index of greater than 10 and a density of less than0.945 g/cc and said propylene polymer is a copolymer of propylene withup to 5 percent by weight ethylene.
 6. A nonwoven fabric according toclaim 4, wherein said polyethylene and said propylene polymer arepresent as distinct phases in the fiber, the propylene polymer beingpresent as the dominant polymer and forming a substantially continuousphase, and said polyethylene being present in an amount less than saiddominant polymer and being dispersed in said continuous phase.
 7. Anonwoven fabric according to claim 2, wherein said two polymers whichare immiscible with one another comprise a propylene polymer andpolyethylene, and wherein said at least one additional polymer ismiscible or partially miscible with said propylene polymer and saidpolyethylene.
 8. A nonwoven fabric according to claim 7, wherein saidadditional miscible or partially miscible polymer is a polyolefin.
 9. Anonwoven fabric according to claim 7, wherein said polymer blendcomprises at least 50% isotactic polypropylene, 1 to 10% polyethylene,and 10 to 40% of said miscible or partially miscible polymer, andwherein said partially miscible polymer is a block or grafted polyolefincopolymer or terpolymer.
 10. A nonwoven fabric according to claim 9,wherein said polymer blend comprises 65 to 80% isotactic polypropylene,15 to 30% of said miscible or partially miscible polyolefin, and 1 to 5%polyethylene.
 11. A nonwoven fabric comprising multipolymer fibersbonded by a plurality of bonds to form a coherent extensible nonwovenweb, and said multipolymer fibers comprising a blend of at least 50%isotactic polypropylene, 1 to 10% polyethylene, and 10 to 40% of a blockor grafted polyolefin copolymer or terpolymer which is miscible orpartially miscible with said polypropylene and said polyethylene.
 12. Anonwoven fabric according to claim 11, wherein said polymer blendcomprises 65 to 80% isotactic polypropylene, 1 to 5% polyethylene, and15 to 30% of said block or grafted polyolefin copolymer wherein at leasta portion of the chain thereof is miscible with isotactic polypropylene.13. A composite nonwoven fabric of at least two layers, said compositefabric comprising at least one layer containing multipolymer fibersbonded by a plurality of bonds to form a coherent extensible nonwovenweb, said coherent extensible nonwoven web having a Taber surfaceabrasion value (rubber wheel) of greater than 10 cycles and anelongation at peak load in at least one of the machine direction or thecross-machine direction of at least 70 percent, and said multipolymerfibers comprising a blend of at least two polymers which are immisciblewith one another and at least one additional polymer which is miscibleor partially miscible with said immiscible polymers.
 14. A compositenonwoven fabric according to claim 13, wherein said blend of immisciblepolymers is comprised of a dominant, continuous phase and at least onedispersed phase.
 15. A composite nonwoven fabric according to claim 14,wherein said blend of immiscible polymers comprises a propylene polymerand polyethylene.
 16. A composite nonwoven fabric according to claim 15,wherein said polyethylene is linear low density polyethylene and saidpropylene polymer is a propylene copolymer or terpolymer.
 17. Acomposite nonwoven fabric according to claim 16, wherein saidpolyethylene is a linear low density polyethylene polymer of a meltindex of greater than 10 and a density of less than 0.945 g/cc and saidpropylene polymer is a copolymer of propylene with up to 5 percent byweight ethylene.
 18. A composite nonwoven fabric according to claim 16,wherein said polyethylene and said propylene polymer are present asdistinct phases in the fiber, the propylene polymer being present as thedominant polymer and forming a substantially continuous phase, and saidpolyethylene being present in an amount less than said dominant polymerand being dispersed in said continuous phase.
 19. A composite nonwovenfabric according to claim 13, wherein said two polymers which areimmiscible with one another comprise a propylene polymer andpolyethylene, and wherein said at least one additional polymer ismiscible or partially miscible with said propylene polymer and saidpolyethylene.
 20. A composite nonwoven fabric according to claim 19,wherein said additional miscible or partially miscible polymer is apolyolefin.
 21. A composite nonwoven fabric according to claim 19,wherein said polymer blend comprises at least 50% isotacticpolypropylene, 1 to 10% polyethylene, and 10 to 40% of said miscible orpartially miscible polymer, and wherein said partially miscible polymeris a block or grafted polyolefin copolymer or terpolymer.
 22. Acomposite nonwoven fabric according to claim 21, wherein said polymerblend comprises 65 to 80% isotactic polypropylene, 15 to 30% of saidmiscible or partially miscible polyolefin, and 1 to 5% polyethylene. 23.A composite nonwoven fabric of at least two layers, said compositefabric comprising at least one layer containing multipolymer fibersbonded by a plurality of bonds to form a coherent extensible nonwovenweb, said multipolymer fibers comprising a blend of at least 50%isotactic polypropylene, 1 to 10% polyethylene, and 10 to 40% of a blockor grafted polyolefin copolymer or terpolymer which is miscible orpartially miscible with said polypropylene and said polyethylene.
 24. Acomposite nonwoven fabric according to claim 23, wherein said polymerblend comprises 65 to 80% isotactic polypropylene, 1 to 5% polyethylene,and 15 to 30% of said block or grafted polyolefin copolymer wherein atleast a portion of the chain thereof is miscible with isotacticpolypropylene.
 25. A composite nonwoven fabric comprising a coherentnonwoven extensible spunbonded web of randomly arranged substantiallycontinuous filaments formed from bicomponent or multicomponentfilaments, at least one polymeric component thereof formed of a blend ofa propylene polymer and polyethylene, said coherent extensible nonwovenweb having a Taber surface abrasion value (rubber wheel) of greater than10 cycles and an elongation at peak load in at least one of the machinedirection or the cross-machine direction of at least 70 percent, anadditional extensible layer, and an adhesive disposed between saidcoherent extensible spunbond web and said additional extensible layer,said adhesive assisting in the connectivity between the spunbond web andthe extensible layer.
 26. A nonwoven fabric according to claim 25,wherein said additional extensible web comprises a polyolefin filmhaving an extensibility of at least 100 percent.
 27. A nonwoven fabricaccording claim 25, wherein said additional extensible web comprises anelastic polyolefin film having an elastic recovery of at least 75percent when elongated 10%.
 28. A composite nonwoven fabric of at leasttwo layers, said composite fabric comprising at least one layercontaining multipolymer fibers comprising at least two polymercomponents arranged into structured domains, at least one polymericcomponent thereof formed of a blend of a propylene polymer andpolyethylene, said fibers bonded by a plurality of bonds to form acoherent extensible nonwoven web, said coherent extensible nonwoven webhaving a Taber surface abrasion value (rubber wheel) of greater than 10cycles and an elongation at peak load in at least one of the machinedirection or the cross-machine direction of at least 70 percent, andsaid composite fabric comprising a second extensible layer attached tosaid coherent extensible nonwoven web.
 29. A nonwoven fabric accordingto claim 28, wherein said multipolymer fibers are bicomponent fiberswith the polymer components thereof arranged in a sheath-core structureddomain.
 30. A nonwoven fabric according to claim 29, wherein saidbicomponent fibers have a polyethylene sheath.
 31. A composite nonwovenfabric of at least two layers, said composite fabric comprising at leastone layer containing fibers formed of a blend of a linear low densitypolyethylene polymer of a melt index of greater than 10 and a density ofless than 0.945 g/cc and a copolymer of propylene with up to 5 percentby weight ethylene, said fibers bonded by a plurality of bonds to form acoherent extensible nonwoven web, said coherent extensible nonwoven webhaving a Taber surface abrasion value (rubber wheel) of greater than 10cycles and an elongation at peak load in at least one of the machinedirection or the cross-machine direction of at least 70 percent, andsaid composite fabric comprising a second extensible layer.
 32. Acomposite nonwoven fabric of at least two layers, said composite fabriccomprising at least one layer containing fibers formed of a blend ofethylene propylene copolymer of a melt index of 20 g/10 min. or less andlinear low density polyethylene, said fibers bonded by a plurality ofbonds to form a coherent extensible nonwoven web, said coherentextensible nonwoven web having a Taber surface abrasion value (rubberwheel) of greater than 10 cycles and an elongation at peak load in atleast one of the machine direction or the cross-machine direction of atleast 70 percent, and said composite fabric comprising a secondextensible layer attached to said coherent extensible nonwoven web.